Elevator bridge



E. E. ALEXANDER 2,473,127

June,l4, 1949.

' ELEVATOR BRIDGE Filed April 26, 1946 i INVENOR. 6614M 6; alarmulerPatented June 14, 1949 UNITED STATES ATENT OFFICE Claims.

My invention pertains to elevators and more particularly to bridge m ansassociated with an elevator adapted to bridge the gap normally existingbetween an elevator floor and a platform on approximately the samelevel. I am aware 5 that those skilled in the art are already familiarwith various devices of this nature as well as with the necessity forsuch devices and the usages thereof. My improved elevator bridgeprovides certain new and novel arrangements compared to prior deviceswhich greatly increase the safety of the elevator and increase the easeof installation and operation.

One of the objects of my invention is to provide an elevator bridgemechanism of the type herein described which is associated with theelevator mechanism in such manner that movement of the elevator whilethe bridge is in a lowered position is prevented.

Among the other objects of my invention is of the bridge; K

Figure 2 is a partially sectioned view indicating the position of theoperating mechanism when the bridge is in a raised position;

Figure 3 is similar to Figure 2 indicating the position of the mechanismwhen the bridge is in w a lowered position; and

Figure 4 is a partially sectioned view illustrating the preferredarrangement of the operating handle and cut-out switch.

Referring to Figure 1, an elevator having a t floor member II isprovided with upwardly extending channel shaped housings l2 attached toan elevator wall I5 adjacent the front of the ele-' vator. The housingsl2 face outwardly forming a hollow section which contains a substantialportion of the operating mechanism. A bridge I3 is attached to the floorI I by hinges I4, or other suitable means, a short distance inwardlyfrom the front edge of the floor and preferably extends laterally thefull length of the floor member II,

being sufficiently wide to bridge the gap normally existing between thecar and an adjacent platform IS. The outer edge of the bridge [3 isbeveled to permit loaded trucks or other vehicles to ride easily overthe edge. The bridge tutes an unnecessary expense and therefore only aI3 is arched, the peak of the arch being generally parallel to the edgeof the floor member I3.

A hinged rod connection or mechanism I I is pivotally attached to thebridge l3 adjacent its outer edge and is also pivotally attached to oneextremity of a bell crank l8. A lever 19 is pivoted to the outer face ofthe housing I 2, a portion of the lever extending outwardly beyond theedge of the housing and being pivotally secured to the rod connection I!at the hinge 2I. The edge of the housing I2 is cut away to permitmovement of the lever IS. The other end of the lever l9 supports anadjustable counterweight 22, the assembly including a counterweight 22and the lever I9 being so constructed and arranged that no portion ofthe mechanism projects outwardly beyond the edge of the elevator floorII, thereby eliminating the need for additional clearance in theelevator shaft.

Rod connection I! is formed in two pieces Fla and Nb joined at thepivotal connection 2| with the lever IS. The point 2| at which the leverI9 is connected to the rod connection I! is selected to position thelever l9 approximately parallel to the bridge IS. The mass and theposition of the counterweight 22 is then selected to balance the weightof the bridge. Since the bridge I3 and the lever l9 are approximatelyparallel, the moment of the counterweight 22 about its pivot will thenbe approximately equal to the moment of the bridge [3 about its hingesl4 in substantially any position of the bridge since in each case themoment decreases as the bridge is brought from a lowered to a raisedposition and increases when moved in a reverse direction.

For convenience in installation, the rod connection I1 is madeadjustable in length. For example, the rod connection I! may be dividedand suitably drilled axially and tapped to receive an adjusting rod 20,having opposite threads at each end whereby rotation of the adjustingrod 20 lengthensor shortens the distance between the bridge and pivotpoint 2i.

The bell crank I8 is journalled in one of the housings l2, extendingthrough the housing at its journal point. One arm 23 of the crank I8 isdisposed within the elevator car and the other arm 28 within the housingI2 for connection to the operating mechanism.

It is to be understood that the herein described mechanism may beprovided in parallel on any elevator car, that is, the mechanism may beduplicated on each side of the elevator in corresponding housings I2.Normally, however, this constiportion of the mechanism comprising aportion of the rod connection l'l', the lever l9 and the counterweight22 with their accompanying pivots are provided on the side opposite thatbearing the actuating mechanism. This type of arrangement is illustratedin Figure 1.

An extremity of the arm 23 is provided with a handle 24 having anaxially aligned pin 26 rigid therewith. The pin 26 extends through anopening 21 formed in an extremity of the arm 23 and is mounted forreciprocable movement therein. A collar 25 is secured to the pin 26 ashort distance inwardly from the arm 23 and a spring 29 is interposedbetween the arm 23 and the collar 25 to normally urge the handle 24 andthe pin 23 outwardly.

A stop member 3| may be formed on the housing l2 to limit the travel ofthearm 23in one direction. At the other end of the arc of theihandle 24,i. e., the raised position, an opening 32 is formed in the housing. I 2to receive the pin 26. A switch 33 having an operating plunger 34 isattached to the housing. [2 with the plunger 34 aligned with the opening32 in such manner that the pin 26 may extend through the opening 32 intocontact with the plunger 34 and under the pressure of the spring 23,force the plunger inwardly tocomplete the circuit through the switch.The switch 33 may suitably be of a spring-actuated normally open type.

While the foregoing disposition of parts constitutes the preferredembodiment of my invention, it is tobe understood that the switch 33 maybe actuated by other portions of the bridge operating mechanism as, forexample, bythe other arm 28 of the bell crank 18. It is also obviouslypossible, where desired, to use a normally closed spring-actuated switchin place of the normally open type of switch whereby movement of thebridge actuating mechanism would hold the switch open except when thebridge I3 is in raised position.

Since most elevators today'are operated by electric power, I havedescribed the use of switch 33 inconnection with my invention. Since theswitch operates to positively interrupt the power supply to the elevatormeans,'i-t is apparent that the elevator cannot be moved except when thebridge member I3 is in raised. position. On ele-- vators powered byothermeans suchv as hydraulic, various obvious modifications may be:made; for example, an auxiliary electric circuit operating power controlmeans; maybe provided and: would include the switch 33 as a part of thecircuit, or, alternatively; a valve could be provided in place oi theswitch 33 interrupting the hydraulic power to the elevator.

One of the principal advantages of my device is that: no portion of themechanism extends outwafil'ly beyond the cube of the elevator in anydirection, either vertically or laterally, and provision, therefore,need. not be made for either side or pit clearance with the attendantpossibility of damage to the mechanism in case of improper operation.

Failure to align. the elevator" properly at floor level, or minormovement of the elevator as: the load increases or decreases will notunduly strain the bridge, since the arched bridge constructionpermitsthe. free end of the bridge tocontact the finer on platform even whenthe elevator is somewhat above or below'the floor level. Even. in theevent the elevator is substantially above thelfioor level, theoperatingmechanism. will. not be severely strained by the arch isdisposed insuch manner as to permit the underside of the bridge to cometo rest on the elevator floor.

My improved linkage provides a continuous, even counterbalance for thebridge in any position and, in addition, my device will positivelyprevent accidental or inopportune operation of the elevator.

In compliance with section 4888 of the Revised Statutes, I haveillustrated and described herein a preferred form of my invention, butit is obvious that many modifications may be made in the details hereindescribed by those skilled in the art Without departing from the truespirit and scope of my invention. I do not therefore wish to be limitedto the precise details herein described except in so far as defined bythe appended claims- Obviously, the same device could be usedadvantageously at loading docks or the like where the space between twoplatforms must be bridged.

I claim:

1. For use with an elevator can having av floor and means for moving thecar, a bridge pivotally secured to the floor of the car adjacent. oneedge thereof, said bridge being of such dimension as to extend outwardlywhen in lowered position beyond the edge of the. car to bridge a gapbetween the car and a platform, upright members attached to the floor ofthe car, a crank arm. pivoted to one of said members, a. rod mechanismpivotally connected to anextremity of said crank and to said bridgemeans, a lever pivoted to said member and pivotally connectedto said rodmechanism, said bridge means. and said lever being substantiallyparallel in all positions, and a counterweight on the opposite end ofsaid lever, the moment of thecounterweiglht about its pivotv beingsubstantially equal to the moment of the sill about the hinge.

2. For use with an elevator car having a floor, members within the cubeof the elevator-extending upwardly from the floor. a housing within thecar attached to one of said members, a bridge pivotally secured to thefloor of the car adjacent one edge thereof, said bridge being of suchdimension as to extend outwardly when in lowered position beyond theedge of the car to bridge a gap between the car and the platform, a bellcrank journal'led through said housing having an outer arm and an innerarm, a rod mechanism pivotally connected to said bridge and to saidinner arm, a lever pivoted to the side of the housing and pivotallyconnected to said rod mechanism, a counterweight 'onthe other end ofsaid lever, the length of said lever being such as to permit movement ofthe counterweight within the channel, the lever being substantiallyparallel to the bridge in all positions whereby the moment of thecounterweight about the pivot 01' the lever may be made substantiallyequalize the moment of the bridge about the hinge, said as-- semblybeing characterized by the absence of bridge operating mechanismprojecting outwardly beyond the cube of the. car in any direction.

3. For use with an elevator car having a bridge hinged to the floor ofthe car adjacent to one edge thereof, said bridge being of suchdimension as to. extend. outwardly beyond the edge of the-car when inlowered position to bridge the gap between the car and a platform,manually operating bridge-actuating means including a pivoted lever, anda counterweight. attached to saidi lever, said lever and said bridgebeing substantially parallel in. all positions whereby the moment so:

5 the counterweight about the pivot of the lever is substantially equalto the moment of the bridge about its hinge.

4:. A bridge for spanning the gap between two platforms, one of which ismovable relative to the other, comprisin an upright member secured toone of the platforms and extending above the fioor thereof, a bridgepivoted adjacent its inner margin to said one platform and adapted whenlowered to span the gap between the two plat-forms, a counterbalancingmechanism for the bridge mounted at least in part on said upright memberand comprising a lever pivoted on said upright member and having one endconnected to the bridge adjacent is outer margin and having acounterweight on the other end of the lever, the arrangement of pivotsand lever arms being such that said lever and bridge are substantiallyparallel at all times with the moment of the counterweight about itspivot being substantially equal to the opposed moment of the bridgeabout its pivot.

5. A bridge for spanning the gap between two platforms, one of which ismovable relative to the parallel at all times with the moment of theother, comprising an upright member secured to 25 counterweight aboutits pivot being substantially equal to the opposed moment of the bridgeabout its pivot, and a crank arm pivotally mounted on said uprightmember and operatively connected to the bridge for moving the bridge toand from its lowered position.

ELISHA E. ALEXANDER.

REFERENCES CITED The following referenlces are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,278,726 Nigh Sept. 10, 19182,120,081 Alexander June 7, 1938

